Method of making a square bottom bag



' April 1, 1969 E. w. P. REICHE 3,435,736

METHOD OF MAKING A SQUARE BOTTOM BAG Filed Oct. 11, 1965 IIVVEIVTORATTORNEYS United States Patent 3,435,736 METHOD OF MAKING A SQUAREBOTTOM BAG Erwin W. P. Reiche, 643 Laurent St., Fabreville, Quebec,Canada Filed Oct. 11, 1965, Ser. No. 494,470 Int. Cl. B31b 49/04 US. Cl.9335 4 Claims ABSTRACT OF THE DISCLOSURE A method of making a squarebottom bag in which triangular flaps formed at the lower corners havetheir walls sealed together before the flaps are sealed to the side orbottom of the bag.

The present invention relates to the manufacture of bags and moreparticularly to the method for the manufacture of bags having a squareor rectangular bottom section.

The invention is particularly directed to a folding process of acontainer having two fiat Walls, the said container being closed on bothside edges and at the bottom edge and opened at the top edge, in orderto obtain a bag having a square or rectangular bottom. The walls arespread apart by known technology to flatten the lower corners of thecontainer and to form a triangular flap at 90 from the plane of theoriginal container. The two surfaces of the said flap are heat sealedtogether in order to prevent the filling material (food or goods) fromentering into the corner flap which would tend to deform the rectangularor square shape of the bottom surface.

The said flap may be cut away leaving a small portion, of the sealedflap in order to maintain the bottom of the bag sealed. The flap mayalso be folded on the side or on the bottom of the bag and sealedthereagainst.

In order to explain the invention in greater details, the followingdrawings are included wherein:

FIG. 1 shows a container in the original form.

FIGS. 2 and 3 show two bags folded in their final shape.

FIG. 4 shows the part of the bag with a cut-away triangular fiap, theflap being shown in dotted lines.

FIGS. 5 and 6 show a section of the lower part of the bag with thetriangular flap respectively extended and cut away.

FIG. 7 shows a bag folded for storage.

A fiat bag such as shown in FIG. 1 is used as a prefabricated container.The said container comprises two walls 2 and 3 closed on both side edges4 and 5 and at the bottom edge 6. The top of the bag is open.

It has been found that it is advantageous to cut or puncture the lowercorners of the bag along the dotted lines A-A of FIG. 1. These puncturedor cut parts allow a better fiow of air through the interior of the bagduring the process of folding the bag.

The lower corners of the bag are pulled apart to form triangular flaps 7and 7 such as shown in dotted lines in FIG. 4. The size of the flap isdetermined by the size and shape of the bag which is folded. The base ofthe triangular flap corresponds to the width of the bag.

FIG. 5 shows the cross-section of the lower part of a bag after the flap7 has been formed. The two surfaces 8 and 9 of the flap 7 are heatsealed together to prevent 3,435,736 Patented Apr. 1, 1969 the materialin the bag from entering between the two surfaces 8 and 9. If the bag ismade of plastic, the two surfaces 8 and 9 may be heat-sealed or gluedwith an appropriate glue.

The triangular flap 7 may be folded upwardly and sealed against the side10 of the bag or folded downwalrdly and sealed against the flat bottom12. The flap may 'be heat-sealed or glued to the sides or the bottom asdescribed for the two surfaces 8 and 9 of the flap 7. FIG. 5 shows thearrow B indicating the rotation of the flap 7 when fixed to the side 10.When the flap is rotated in the direction shown by the arrow C, the saidflap is sealed against the bottom 12.

It is pointed out that the sealed portions help to rigidify the lowersection of the bag. The sealing of the two surfaces 8 and 9 addstherefore to the rigidity of the lower section of the bag.

If the additional rigidity provided by the-flap 7 is not needed or iffor some other reasons, such as economy of space or weight, the flap 7is not wanted, the major part of the flap is cut away as shown in FIG.6. The base 13 of the said flap is not removed. The remaining part 13 ofthe flap 7 seals the bottom 12 and sides 10 in order to prevent theescapement of the material in the bag.

In order to facilitate the storage of the bags, the latter are foldedflat one over the other. Accordingly, the bags are creased along thelines 14 corresponding to the top edges of the flaps 7 and 7' as if thelatter are folded upwardly as shown in FIG. 3. At least one of the wallsis also creased on line 15 across the full width at the level of the topapexes of the flap as shown in FIG. 3 so that the lower part of the bagmay be folded as shown in FIG. 7.

As it may be seen from the above description, a fiat bag, such as shownin FIG. 1, which is easily available on the market, may be commonlyfolded into a bag having a square or rectangular bottom the lowersection of the bag being simply sealed. With this process it is possibleto obtain from the same original container a plurality of proportionsbetween the sides of the finished bag. The sealed portion of the flapsformed in the lower portion of the bag may be used to reinforce the saidportion.

Although a specific embodiment of the invention has just been described,it will be understood that various modifications may be made theretowithout departing from the invention, the scope of which is only to beconstrued from the appended claims.

I claim:

1. In the manufacture of a square or rectangular bottom bag, a processfor folding a nonfibrous plastic container having two fiat walls, saidcontainer being closed on both side edges and at the bottom edge, andopened at the top edge, comprising spreading apart the walls at thelower corners of the container, forming in the lower corners of thecontainer a triangular flap at substantially with the plane of thewalls; heat-sealing the walls together inside the said triangular flap,folding and sealing the said flap on the side or on the bottom of thebag.

2. In the manufacture of a bag, as recited in claim 1, wherein thecorners of the container are punctured prior to spreading the wallsapart.

3. In the manufacture of a bag as recited in claim 1, wherein the wallsare creased along the line correspond- 3 ing to the top edges of theflap when the latter is folded upwardly, at least one of the walls beingalso creased across their full width at the level of the top apex of theflaps.

4. In the manufacture of a square or rectangular bottom bag, a processfor folding a non-fibrous container having two flat walls, saidcontainer bein closed on both side edges and at the bottom edge, andopened at the top edge, comprising spreading apart the top walls at thelower corners of the container, forming in the lower corners of thecontainer a triangular flap at substantially 90 with the plane of thewalls, heat-sealing the walls together inside the said triangular flap;and cutting off 4 the major portion of the flap leaving a sealed edgealong the base of the triangular flap.

References Cited UNITED STATES PATENTS 2,070,747 2/1937 Orstrom 229-602,810,328 10/1957 Seltmann et a1. 93--35 2,985,355 5/1963 Read.

3,025,768 3/1962 Kessler 93-35 10 3,150,573 9/1964 Piazze 93-35 BERNARDSTICKNEY, Primary Examiner.

